Answer whether the receiver can be considered sufficiently
close to num (this is done by checking equality if num is
not a number, and by checking with 0.01% tolerance if num
is a number).
even
Returns true if self is divisible by 2
isFinite
Answer whether the receiver represents a finite quantity. Most
numeric classes are for finite quantities, so the default is to
answer true rather than calling #subclassResponsibility.
isInfinite
Answer whether the receiver represents an infinite quantity. Most
numeric classes are for finite quantities, so the default is to
answer false rather than calling #subclassResponsibility.
isNaN
Answer whether the receiver is a Not-A-Number. Most numeric
classes don't handle nans, so the default is to answer false
rather than calling #subclassResponsibility.
isNumber
Answer `true'.
isRational
Answer whether the receiver is rational - false by default